The present invention relates to ways of adding protection against accidental needle-stick to hypodermic syringes and, more particularly, to apparatus for providing passive protection against accidental needle-stick for a hypodermic needle extending from a hub comprising, a tip protector comprising a cross-piece disposed transverse to the needle having an elongated first bore therethrough through which the needle passes and having a bell-shaped tip-guard extending from the cross-piece concentrically about the first bore and covering a tip portion of the needle with the tip protector in an extended position, the tip protector being slidably moveable along the needle supported by the elongated first bore between the extended position and a retracted position with the tip portion of the needle exposed for use; guide means for guiding the tip protector between the extended position and the retracted position; spring means biasing the tip protector to the extended position; and, releasable locking means for automatically releasably locking the tip protector in the extended position when the tip protector moves to the extended position from a position retracted therefrom.
A standard hypodermic syringe 10 as depicted in FIG. 1 has a cylindrical body 12 with a needle 14 extending from one closed end and a sliding plunger 16 extending from an opposite open end. Accidental needle-stick by medical workers has always been an annoyance an a minor medical risk that went with the job. Current statistics say that about 2,700 medical workers get stuck with used needles every day. With contemporary problems such as HIV/AIDS and Hepatitis-B, however, accidental needle-stick has become more than a mere annoyance and minor medical risk. The fear and long uncertainty about having contracted the HIV virus from an accidental needle-stick alone has turned this phenomenon into a national medical crisis.
While there have long been many inventions known in the art for avoiding or at least minimizing the chances of accidental needle-stick, most of them have problems that have prevented their general acceptance at this time. When syringes were reused following autoclaving, initial cost was not a factor and expensive syringes with retractable needles, and the like, could have been successful. With the advent of plastics, however, the disposable syringe became practical thereby eliminating the need for costly and time-consuming autoclaving equipment and processes. Where a standard, unprotected syringe as in FIG. 1 sells in bulk for six cents, a protected version must sell for less than a dollar to be competitive and commercially successful. Several needle protectors have recently been introduced which seek to provide a simple and low-cost solution to the needle-stick problem.
The version of Thomas Kuracina which is the subject of U.S. Pat. No. 4,998,922 is depicted in FIG. 2. There is a protective sleeve 18 comprised of a plurality of longitudinal slats 20 terminating in an end-bell 22. A spring-biased locking collar 24 is positioned over the sleeve 18. By retracting the locking collar 24 against the force of the spring 26, the end-bell 22 can be retracted to expose the needle 14 for use. As the end-bell 22 retracts, the slats 20 bend to the ghosted position shown. When a retracting force on the end-bell 22 is removed (as by withdrawing the needle 14), the self-biasing force of the plastic of the slats 20 moves the end-bell 22 to its extended position covering and protecting the tip of the needle 14. As soon as the slats 20 resume their cylindrical extended shape, the locking collar 24 is pushed forward by the spring 26 thus locking the slats 20 against rebending and the end-bell 22 from retracting. As can be realized from the foregoing description, the Kuracina device is a passive device in that the needle tip is automatically covered when the needle is withdrawn without any action being required on the part of the user. By contrast, a prior art active protective device is shown in FIG. 3. In this case, there is a hard, cylindrical, plastic sleeve 28 slidingly mounted over the body 12 of the syringe 10. For use, the sleeve 28 is retracted as shown to expose the needle 14. After use, the sleeve 28 is manually slid to the ghosted position where it snaps and locks in place.
Since most accidental needle sticks are of the "oops" variety taking place, before the user even has a chance to take any affirmative action to cover the needle as with the sleeve 28 of FIG. 3, passive protective devices are preferred.
In U.K. published Patent Application number GB 2-202-747 A of Dr. William Ducat, a passive hard sleeve protective device as depicted in FIG. 4 is disclosed. The hard sleeve 28 is biased by the spring 26 towards its extended position as shown. An L-shaped locking channel (not shown) on the outer surface of the syringe body 12 interacts with a pin (not shown) on the inner surface of the sleeve 28 to provide an automatic locking action for the sleeve 28. To release the sleeve 28 so that it can be retracted, the sleeve 28 is manually twisted against the torque of the spring 26. When the needle is withdrawn and the sleeve 28 moves forward, when the pin reaches the cross-piece of the "L", the torque of the spring 26 moves the pin into the cross-piece automatically locking the sleeve 28 from further retraction unless and until it is manually twisted again. Obviously, a permanent locking arrangement as employed with the sleeve 28 of FIG. 3 could be added such that after the syringe 10 of FIG. 4 was used and the sleeve 28 was in its releasable locked position, further sliding it forward would cause the permanent lock to set so that the syringe 10 could not be used further. With or without the permanent lock, a hard-sleeve based protective system will generally withstand more longitudinal force without exposing the needle tip than a bendable slat-based system such as that of FIG. 2.
The problem with the spring-biased sleeve of FIG. 4 is that the sleeve 28 moves back over the body 12 of the syringe 10. In the version of FIG. 3, that is not a problem because the syringe 10 is gripped over the retracted sleeve 28 for use and then the sleeve 28 is manually extended. Where automatic (i.e. passive) extension is desired, gripping the syringe 10 by means of the sleeve 28 will interfere with the automatic action of the sleeve 28. Thus, unless special care is taken, the passive protective action may be defeated. Generally, medical workers do not want to use anything that requires deviation from their normal procedure. This could explain from at least one point of view why Dr. Ducat's needle protector is not in general use. Also, this apparatus requires that the syringe body 12 be modified so as to provide the L-shaped locking slot therein. In general, apparatus that can be used with standard components is preferred from both the manufacturing and user point of view. For example, while the Kuracina apparatus of FIG. 2 is pictured built into a unitary syringe, it can be made with the needle 14 and sleeve 18 assembly attached to a standard threaded hub which attaches to a standard syringe body 12 made for such purposes.
Wherefore, it is an object of this invention to provide a passive needle protector for syringes which provides a high degree of longitudinal force resistance like a hard-sleeve system.
It is another object of this invention to provide a passive needle protector for syringes which operates on a sliding sleeve type of approach while not interfering with normal operation of the syringe.
It is still another object of this invention to provide a passive needle protector for syringes which operates on a sliding sleeve type of approach while not requiring any modification to the syringe.
Other objects and benefits of this invention will become apparent to those skilled in the art from the detailed description which follows hereinafter when taken in conjunction with the drawing figures which accompany it.